The development and utilization of new energy sources has been extensively studied in the world. Here, we report the development of flexible self-supported metal-free electrodes based on non-oxidized graphene multilayer (MLG) paper containing the lead iodide nanoparticles (PbI2-NPs). The PbI2-NPs was obtained and characterized by X-ray diffraction (XDR) and Raman spectroscopy. Supercapacitor containing the PbI2-NPs in MLG electrodes was fabricated by a simple method and characterized using atomic force microscopy (AFM), cyclic voltammetry (CV) and galvanostatic charge-discharge techniques. The results show a flexible supercapacitor fashion reaching capacitance values of 154 F/g with high prospects in electronic area. Energy and power densities obtained for the pure MLG supercapacitor were 3.40 µWh cm-2 and 0.73 mW cm-2, respectively. Regarding to PbI2-NPs/MLG capacitor the energy and power density obtained were 3.50 Wh kg-1 and 1.10 kW kg-1. The results herein presented open the possibility to new energy storage devices using PbI2-NPs and MLG flexible supercapacitor configuration.

In this paper, we present an alternative method to obtain thin films for coating protection on the surface of the AA2524-T3 Al-alloy by using the Layer-by-Layer (LbL) technique. The LbL films were fabricated by alternated immersion of the Al-alloy into a poly(styrene sulfonate) (PSS) and polyaniline nanoparticles (PAni-NPs) solutions, obtaining a PAni-NPs/PSS bilayer architecture. The LbL films were characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), electrochemical and micro-abrasive wear tests. The results show that the number of bilayers promotes shifts to less negative potentials, indicating an optimized system, in which the best performance was observed for a 15-bilayer PAni/PSS LbL film. The pitting potential (Epit) values shifted 130 mV (from -610 mV to -480 mV) in comparing a bare Al-alloy. The predominantly wear mechanism for AA2524-T3 with PAni-NPs/PSS bilayers was scratching whereas for the bare material there was an equivalence between scratching and rolling mechanisms. The results proved that the incorporation of PAni-NPS by the LbL method may be propitious as protective coating against corrosion in AA2524-T3 alloy.

ABSTRACT Vanadium oxide films amorphous, nonstoichiometric and highly absorbing in the optical region were deposited on ITO-coated glass and on silicon substrates, by the hot-filament metal oxide deposition technique (HFMOD) and oxidized by ex-situ annealing in a furnace at 200, 300, 400 and 500 ºC, under an atmosphere of argon and rarefied oxygen. X-ray diffraction, Raman and Rutherford backscattering spectroscopy as well as optical transmission were employed to characterize the amorphous and annealed films. When annealed at 200 and 300 ºC the as-deposited opaque films become transparent but still amorphous. Under treatments at 400 and 500 ºC a crystalline nonstoichiometric V2O5 structure is formed. All the annealed films became semiconducting, with their optical absorption coefficients changing with the annealing temperature. An optical gap of 2.25 eV was measured for the films annealed at 400 and 500 ºC. The annealing in rarefied oxygen atmosphere proved to be a useful and simple ex-situ method to modulate the structural and optical properties of vanadium oxide films deposited by HFMOD technique. This technique could be applied to other amorphous and non-absorbing oxide films, replacing the conventional and sometimes expensive method of modulate desirable film properties by controlling the film deposition parameters. Even more, the HFMOD technique can be an inexpensive alternative to deposit metal oxide films.

RESUMO O trabalho em questão está relacionado ao projeto e construção de uma fonte de alta tensão em corrente contínua utilizando materiais e dispositivos adquiridos no comércio local visando sua aplicação no processo de pulverização catódica. Essa técnica permite a deposição de filmes finos de metais, óxidos e nitretos sobre substratos sólidos. Como teste de funcionamento e aplicação da fonte DC, com a mesma instalada em canhão de pulverização em alto vácuo, filmes finos de diferentes espessuras de cobre, aço inoxidável 304 e tungstênio foram depositados e estudados. Análise de espessura, morfologia, e resistência elétrica e resistividade foram conduzidas. Filmes com resistividade elétrica dependente das espessuras foram obtidos. A fonte DC se mostrou confiável em operação e permite a deposição de uma infinidade de materiais nas mais diferentes espessuras sobre vários tipos de substratos.

ABSTRACT This work is related to the project and construction of a DC high voltage power supply using materials and electronic devices acquired in local stores and to be used in sputtering proposes. The technique allows the obtainment of several kinds of thin films such as metals, oxides, nitrides and others upon solid substrates. In order to perform a test, the DC power supply was installed in a high vacuum system, connecting the power supply directly in a magnetron sputtering gun. Thin films of copper, stainless steel 304 and tungsten of several thickness were deposited upon commercial glass slides. The film thickness, surface morphology, electric resistance, sheet resistance and resistivity were herein analyzed. The power supply shows a good reliability in operation and allows the deposition of several materials in various thickness and substrates.

A dip coating system was projected and constructed to deposit a large range of thin films onto solid substrates. A microcontroller was used to control the deposition system. As an example of application multilayer graphene (MLG) films were deposited onto glass slices in order to obtain conductive films with relatively good light transmittance. The MLG flakes were obtained using natural graphite and isopropyl alcohol resulting in three dispersions treated in ultrasound for 30, 60 and 90 minutes, respectively. Using atomic force microscopy, UV-Vis spectrometry and an electrometer the film characterizations were performed. MLG flakes about 13 nm thick, 10 mµ2 of area were observed using AFM. In films obtained with 35 immersions the electrical resistance and the resistance sheet reached 1.8 kΩ and 1.9kΩ/square respectively. The light transmittance reached 10-20% while films obtained with dispersions treated for 60 and 90 minutes were electrically continuous. Thus, conductive films can be used in chemiresistor sensors, electrochemical and supercapacitors electrodes.

Carbon nanostructures (nanotubes, nanofibers and nanosponges) were synthesized onto Si (001) substrates using a microwave assisted plasma enhanced chemical vapor deposition (PECVD) from C2H2-Ar mixtures at low substrate temperatures (120 °C). Catalytic films (Ni and Cu) 3 nm thick were used. Different structures were formed, depending on the C2H2 partial pressure. Atomic force microscopy (AFM) and scanning electron spectroscopy (SEM) were employed for the morphological characterization of the catalytic films and the carbon nanostructures, respectively. Raman spectroscopy was used to identify carbon hybridization states. AFM was used to observe the morphology of the catalytic films. At low C2H2 partial pressures, nanotubes with nanospheres in their tips, growing from nanoholes were seen. With increasing C2H2 pressures, longer nanotubes were observed, reaching lengths from 300 to 500 nm. In their growth, the nanotubes laterally touch each other, forming nanotube bundles, or nanofibers. For the higher C2H2 partial pressures, dense sponge-like (nanosponge) structures, consisting of a large number of bundles, are formed. From the Raman spectra, a mixture of sp2 and sp3 hybridizations were identified. Furthermore, the low substrate temperature at which depositions can be carried out, makes possible growth of carbon nanostructures on materials to which high temperatures would be deleterious.

OBJETIVO: Investigar a influência das técnicas de reprocessamento de banho enzimático com limpeza ultrassônica e a esterilização com óxido de etileno nas propriedades químicas e estruturas morfológicas de revestimentos poliméricos de fios-guia usados como guias em cateteres regulares. MÉTODOS: Estas técnicas simulam a rotina de processamento de fios-guia em muitos serviços de hemodinâmica do Brasil e de outros países. Amostras de três diferentes fabricantes foram verificadas por microscopia eletrônica de varredura e espectroscopia de fotoelétrons de raios-X. RESULTADOS: Uma única ou dupla esterilização dos cateteres com óxido de etileno não foi associada a mudanças químicas ou morfológicas. Contudo, imagens de microscopia eletrônica de varredura mostraram que o método de lavagem foi associado a intensas modificações morfológicas, incluindo bolhas e buracos superficiais, assim como mudanças nas ligações químicas das camadas atômicas externas do revestimento polimérico, conforme demonstrado por resultados de espectroscopia de fotoelétrons de raios-X, compatível com extensas modificações químicas induzidas por esse processo de lavagem. CONCLUSÃO: O reprocessamento dos fios-guia de cateteres com óxido de etileno não está associado a mudanças químicas e morfológicas dos mesmos e pode ser considerado adequado para manter a integridade destes materiais. Entretanto, o método que combina lavagem química com vibração mecânica resulta em intensas deteriorações anatômicas e químicas, sugerindo que esse método de processamento deve ser desencorajado.

OBJECTIVE: To investigate the influence of the reprocessing technique of enzymatic bath with ultrasonic cleaning and ethylene oxide sterilization on the chemical properties and morphological structure of polymeric coatings of guide wire for regular guiding catheter. METHODS: These techniques simulated the routine of guide wire reprocessing in many hemodynamic services in Brazil and other countries. Samples from three different manufacturers were verified by scanning electron microscopy and X-ray photoelectron spectroscopy. RESULTS: A single or double sterilization of the catheters with ethylene oxide was not associated with morphological or chemical changes. However, scanning electron microscopy images showed that the washing method was associated with rough morphological changes, including superficial holes and bubbles, in addition to chemical changes of external atomic layers of polymeric coating surfaces, as detected by the X-ray photoelectron spectroscopy method, which is compatible with extended chemical changes on catheter surfaces. CONCLUSION: The reprocessing of the catheters with ethylene oxide was not associated with morphological or chemical changes, and it seemed appropriate to maintain guide wire coating integrity. However, the method combining chemical cleaning with mechanical vibration resulted in rough anatomical and chemical surface deterioration, suggesting that this reprocessing method should be discouraged.